Rarely, ACE inhibitors have been associated with a syndrome that starts with cholestatic jaundice and progresses to fulminant hepatic necrosis and (sometimes) death. The mechanism of this syndrome is not understood. Patients receiving ACE inhibitors who develop jaundice or marked elevations of hepatic enzymes should discontinue the ACE inhibitor and receive appropriate medical follow-up.
As a consequence of inhibiting the renin-angiotensin-aldosterone system, changes in renal function may be anticipated in susceptible individuals. In patients with severe congestive heart failure whose renal function may depend on the activity of the renin-angiotensin-aldosterone system, treatment with angiotensin-converting enzyme inhibitors, including benazepril hydrochloride, may be associated with oliguria and/or progressive azotemia and (rarely) with acute renal failure and/or death. In a small study of hypertensive patients with renal artery stenosis in a solitary kidney or bilateral renal artery stenosis, treatment with benazepril hydrochloride was associated with increases in blood urea nitrogen and serum creatinine; these increases were reversible upon discontinuation of benazepril hydrochloride or diuretic therapy, or both. When such patients are treated with ACE inhibitors, renal function should be monitored during the first few weeks of therapy. Some hypertensive patients with no apparent preexisting renal vascular disease have developed increases in blood urea nitrogen and serum creatinine, usually minor and transient, especially when benazepril hydrochloride has been given concomitantly with a diuretic. This is more likely to occur in patients with preexisting renal impairment. Dosage reduction of benazepril hydrochloride and/or discontinuation of the diuretic may be required. Evaluation of the hypertensive patient should always include assessment of renal function ( see DOSAGE AND ADMINISTRATION).
In clinical trials, hyperkalemia (serum potassium at least 0.5 mEq/L greater than the upper limit of normal) occurred in approximately 1% of hypertensive patients receiving benazepril hydrochloride. In most cases, these were isolated values which resolved despite continued therapy. Risk factors for the development of hyperkalemia include renal insufficiency, diabetes mellitus and the concomitant use of potassium-sparing diuretics, potassium supplements and/or potassium-containing salt substitutes, which should be used cautiously, if at all, with benazepril hydrochloride (see PRECAUTIONS , Drug Interactions).
Presumably due to the inhibition of the degradation of endogenous bradykinin, persistent nonproductive cough has been reported with all ACE inhibitors, always resolving after discontinuation of therapy. ACE inhibitor-induced cough should be considered in the differential diagnosis of cough.
In patients with hepatic dysfunction due to cirrhosis, levels of benazeprilat are essentially unaltered (see WARNINGS , Hepatic Failure).
In patients undergoing surgery or during anesthesia with agents that produce hypotension, benazepril will block the angiotensin II formation that could otherwise occur secondary to compensatory renin release. Hypotension that occurs as a result of this mechanism can be corrected by volume expansion.
Female patients of childbearing age should be told about the consequences of exposure to ACE inhibitors. Discuss other treatment options with women planning to become pregnant. Patients should be asked to report pregnancies to their physicians as soon as possible.
Angioedema, including laryngeal edema, can occur at any time with treatment with ACE inhibitors. Patients should be so advised and told to report immediately any signs or symptoms suggesting angioedema (swelling of face, eyes, lips or tongue or difficulty in breathing) and to take no more drug until they have consulted with the prescribing physician.
Patients should be cautioned that lightheadedness can occur, especially during the first days of therapy, and it should be reported to the prescribing physician. Patients should be told that if syncope occurs, benazepril hydrochloride tablets should be discontinued until the prescribing physician has been consulted.
All patients should be cautioned that inadequate fluid intake or excessive perspiration, diarrhea or vomiting can lead to an excessive fall in blood pressure, with the same consequences of lightheadedness and possible syncope.
Patients should be told not to use potassium supplements or salt substitutes containing potassium without consulting the prescribing physician.
Patients should be told to promptly report any indication of infection (e.g., sore throat, fever), which could be a sign of neutropenia.
Patients on diuretics, especially those in whom diuretic therapy was recently instituted, may occasionally experience an excessive reduction of blood pressure after initiation of therapy with benazepril hydrochloride. The possibility of hypotensive effects with benazepril hydrochloride can be minimized by either discontinuing the diuretic or increasing the salt intake prior to initiation of treatment with benazepril hydrochloride. If this is not possible, the starting dose should be reduced (see DOSAGE AND ADMINISTRATION).
Benazepril hydrochloride can attenuate potassium loss caused by thiazide diuretics. Potassium-sparing diuretics (spironolactone, amiloride, triamterene and others) or potassium supplements can increase the risk of hyperkalemia. Therefore, if concomitant use of such agents is indicated, they should be given with caution, and the patient’s serum potassium should be monitored frequently.
Interaction studies with warfarin and acenocoumarol failed to identify any clinically important effects on the serum concentrations or clinical effects of these anticoagulants.
Increased serum lithium levels and symptoms of lithium toxicity have been reported in patients receiving ACE inhibitors (including benazepril) during therapy with lithium. These drugs should be coadministered with caution, and frequent monitoring of serum lithium levels is recommended. If a diuretic is also used, the risk of lithium toxicity may be increased.
In rare cases, diabetic patients receiving an ACE inhibitor (including benazepril) concomitantly with insulin or oral anti-diabetics may develop hypoglycemia. Such patients should therefore be advised about the possibility of hypoglycemic reactions and should be monitored accordingly.
No clinically important pharmacokinetic interactions occurred when benazepril hydrochloride was administered concomitantly with hydrochlorothiazide, chlorthalidone, furosemide, digoxin, propranolol, atenolol, naproxen or cimetidine.
Benazepril hydrochloride has been used concomitantly with beta-adrenergic-blocking agents, calcium-channel-blocking agents, diuretics, digoxin and hydralazine, without evidence of clinically important adverse interactions. Benazepril, like other ACE inhibitors, has had less than additive effects with beta-adrenergic blockers, presumably because both drugs lower blood pressure by inhibiting parts of the renin-angiotensin system.
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